The run-times of portable devices (e.g., cell phones, PDA's, etc.) are limited by the size of the battery packs used to power these devices. Generally, the battery packs are recharged by connecting the batteries and/or the devices to chargers that receive power from external AC or DC power sources.
When a user travels, and does not have access to the typical external power sources used to recharge the battery packs powering the user's various portable devices, the user is generally required to carry extra batteries for each portable device he has to extend the use time of those devices.